Gem::Security::Signer#sign

# File tmp/rubies/ruby-3.0.5/lib/rubygems/security/signer.rb, line 139
def sign(data)
  return unless @key

  raise Gem::Security::Exception, 'no certs provided' if @cert_chain.empty?

  if @cert_chain.length == 1 and @cert_chain.last.not_after < Time.now
    alert("Your certificate has expired, trying to re-sign it...")

    re_sign_key(
      expiration_length: (Gem::Security::ONE_DAY * options[:expiration_length_days])
    )
  end

  full_name = extract_name @cert_chain.last

  Gem::Security::SigningPolicy.verify @cert_chain, @key, {}, {}, full_name

  @key.sign @digest_algorithm.new, data
end